GMC Jimmy (K5 Blazer) 5.3 Vortec 3 link coil spring build.

[Wally'sJimmy]

Hey everyone, I just wanted to share my build. Truck is a 1977 GMC Jimmy High Sierra. I saw the truck in Sept of 2013 on Craigslist for $1500 with a bad engine in Casa Grande but I was really looking for a 73-75 K5, my dad had a 74 when I was a kid so I guess its a sentimental thing. (Here's a couple pics)


So after looking at a bunch a either overpriced or complete garbage full top blazers I decided to go look at this one. When we go down there I was surprised, here was a completely original Jimmy that really hadn't been touched other that a few cosmetic things. It had a knocking 400, turbo 350/203, 12 bolt rear, dana 44 front. It had all the original interior and original paint. After talking with the seller for a bit I found out he bought it as a project for himself from the Schneph Farms family which is a well known farming family here in AZ. Ray Schneph bought it new in 77 as his personal vehicle. So after some haggling I got it for $1200 loaded it up and brought it home.



So now I had to figure out what I wanted to do with it.

 

[chilliwak]

WOW What a cool looking rig! It looks to be in great shape except for the knocking motor!

 

[Wally'sJimmy]

After trying to figure out what I wanted to do I decided to make it a daily driver and my primary vehicle. So deconstruction began,




I decided to go all out and gut everything. Being an old farm truck it had alot of sand and mud under the truck. I brought home a steam cleaner from work layed on the creeper and went to work!


Now that i got that out of the way I needed to find an engine, Caigslist to the rescue again and off on another road trip to Tucson for this,


A complete 5.3 with all the wiring and accessories for $700.

Next I had to get the engine cleaned up, inspected and ready to test fit.

 

[Wally'sJimmy]

WOW What a cool looking rig! It looks to be in great shape except for the knocking motor!

Thanks, I was suprised how nice it was. It does have a little rust in the drivers rocker and passenger lower fender. The rest of the truck is perfect. The funny thing is that was almost a deal breaker for me LOL I hate rust! Being an AZ native it's not something i'm use to.

 

[jonnyquest]

Subscribed. This is going to be good.

 

[Wally'sJimmy]

Hope everyone had a great holiday weekend!

Now that everything was clean and checked out I painted the frame and axle, installed a set of 2.5 lift springs in the front along with ORD greasable shackles and new shocks. Now the engine was ready to go in. I probably had that thing in and out 5 times making changes along the way.





The mounts I chose were from Dirty Dingo here in the valley. I liked the adjustability because I wanted the engine as far back as possible. They turned out to be not so great but I'll get into that later.

First test fit revealed two problems, the block hit the stock crossmember and the exhaust manifold hit the frame on the passenger side.





The research that I had done before hand mentioned both those problems. Because I was using adjustable motor mounts I was hoping to slide the engine back far enough to clear both issues, oh well
For the exhaust I had two choices, cut the frame or do what the budget turbo guys do and cut the flanges off the manifolds and weld on 2.5" V-Bands. I chose the ladder.







The LS manifolds have a high steel content and will weld just like steel. The V-Bands are mild steel and they welded on perfectly, it's been 3 years and I've had no issues. This also allowed me to angle the pipe anywhere I wanted it.

 

[Wally'sJimmy]

The stock crossmember was cut out and a new one form ORD was fitted. I had to use their big block crossmember for more clearance but that still didn't clear the oil pan so I made 1" spacers to make it all fit right.

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As for the motor mounts, when I install the engine the tabs were hitting the frame. So after making some adjustments I still could not get it the way I wanted so I emailed Dirty Dingo. I sent them pictures and explained my problem. So after a vague response I called them, after our conversation he basically told my "well we have sold a lot of these and we don't know of any problems". The other issue is the mount pushes on the rubber in the clamshell and causes it to slide to the bottom of the mount (see pics). After getting no help I needed to keep moving forward, so I ground the mounts for clearance and ran them.





After less than 100 miles this is what they looked like. Funny thing is they later changed the design of the mount from the elongated hole to a standard hole.

 

[upsidedown2]

We are just finishing up a LQ4 6.0 in my sons 1986 Chevy truck. The swap is so easy did the harness ourselves. You will love the way they run so much better than old school.

 

[Wally'sJimmy]

We are just finishing up a LQ4 6.0 in my sons 1986 Chevy truck. The swap is so easy did the harness ourselves. You will love the way they run so much better than old school.

I already do! :wings: Its been together for about 2 years now and your right, what a difference over old school, it was well worth the effort. I never considered an LS swap but my friend who owns a machine shop here in the valley talked me into it. He builds a tone of these things from mild to wild.

 

[Wally'sJimmy]

Now that the engine was ready to go I picked up a freshly built 4L60E



Now I had to work out the trans and t-case adapter. For that I went to Advanced Adapters for their 6 bolt to 4 bolt adapter.



The adapter allows you to adapt the 6 bolt 4L60E pattern to a 4 bolt pattern found on the stock trans to T-case adapter. It also has provisions for speed sensors and the reluctor wheel for the computer.







The trans and transfer case went in next. I just used a 208 T-case for the time being, a 241C will most likely be a future project.

 

[Wally'sJimmy]

When I bought the engine it had ALL the wiring, computer even the gas peddle (DBW). I really wasn't sure what I wanted to do, buy a new harness, rework mine myself or have the stock one reworked. New harness were crazy money upwards of $1500 or so, everyone in town or nearby states wanted $600-$800 to rework it and to be honest I was intimidated doing it myself. I've never really had the patience for wiring (I do now) I knew I wanted to use the stock truck harness, I didn't care what it looked like as long as it was clean, its a truck. After a lot of searching I found Wait for Me Performance in Indiana. I gave Jesse a call and for $360 he re worked my harness for what I was doing, flashed the ECM and installed a tune and that included the return shipping! The harness came back with everything tagged and ready to install.





Next I made a mount for the computer





The wiring turned out to be super easy, everything laid out in the stock location, all I had to do was plug it in. The gas peddle was the only challenging part. I had to cut the peddle off the DBW peddle and I cut the linkage from the Jimmy's stock peddle and welded them together. When you look in the truck you cant even tell!



Once that was done I could begin final assembly!



Next would be the fuel system.

 

[Wally'sJimmy]

The fuel system for this build was super easy. I explored all my options as far as fuel pumps, external, internal, size, brand and so on. I decided to go with the PA4 from Tanks Inc. For $250 you get a drop in height adjustable sending unit with an OE quality Walbro fuel pump.



I wanted an in-tank pump for reliability and they say it runs much cooler. I lost the pics of the installation but you can find all the info you need on their website.



Here you can see it installed into the stock tank



I used all braded steel fuel line with AN fittings and a Corvette filter/regulator, ran one wire from the pump to a relay which the computer controls and that's it!





Once all that was done it was a lot of time cleaning everything up, wrapping wires and putting everything together. Time to see if it runs!

[video]https://youtu.be/Kb80GGiQc-8[/video]

After that it was off the exhaust shop for a 2.5" full length system with flowmasters and 3" tips (which I would later change lol). here are some pics before I did the AC work.

 

[Atl-atl]

So cool! Cant wait to see updated exterior shots. I have a feeling itll look really good, and youll probably post them here in a few minutes hahaha. :sombrero:

 

[Wally'sJimmy]

Here ya go!!

I found some rally wheels, cleaned them up put new caps and trim rings on and some 33/12.5-15 Duratracs.









I rebuilt the AC system had custom lines made for the Sanden compressor and used hi mount brackets from Alan Grove.

 

[Wally'sJimmy]

Next project would be the suspension.